Mooring limbs, legs, tethers, or lines, are required for mooring objects, such as ships, pontoons, and buoys so that they do not move too much relative to the land beneath the surface of the water. To more closely limit the movement of such an object it is known to use more than one limb, possibly at either end of a ship, for instance. Known mooring limbs typically comprise ropes or chains. There are two principal kinds of mooring limbs. The first are taught in use, and the second are slack in use. The present invention may be either taught and/or slack in use.
To allow for the rise and fall of the water level on which a moored object is floating due to, for instance, tides or waves, a certain amount of slack must be provided in the length of a slack-type limb. However, this allows for the object to move “off station” when the water level is lower than the highest level catered for by the slack. Although this is not a problem for most applications, it can cause problems for objects, such as pontoons or wave energy converters, which need to remain substantially “on station” and yet be able to rise and fall with, for instance, the tides.
A known system which overcomes this problem is provided in the form of a resilient limb comprising rubber-type materials. These limbs allow for an extension and contraction of their longitudinal length whilst maintaining tension therein. This allows for the object to rise and fall with the tides, waves and other movements of the water whilst remaining on station.